Speech production will be compared for patients with restrictive, obstructive, and neuromuscular chest wall diseases, and for normal subjects. The effect of respiratory diseases of various types and degrees of severity upon the spoken voice will be studied systematically. All subjects will have standard pulmonary function tests of lung volumes and mechanics. A series of utterances then will be recorded, using a prescribed protocol. The protocol is designed to include continuous speech as well as phonetically balanced productions and activities which will stress the speech mechanisms. Airflow and lung volume will be recorded simultaneously, on different channels of the same magnetic tape. A Respitrace induction plethysmograph will be used to allow measurement of the relative contributions of thoracic and abdominal breathing. Intraoral pressure and pneumotachygraph flow rates will be measured for some parts of the protocol. Frequency, intensity, and temporal aspects of the sound signal will be analyzed, and speech characteristics assessed perceptually. Analysis of the data will test hypotheses that lung diseases and physiologic limitations will alter speech characteristics. These alterations will be measured and correlated with physiologic changes and compensatory mechanisms adopted by the subjects. Analytic techniques will include sound intensity and spectrum analysis, using computer techniques to relate these to physiological variables, and subjective assessment of vocal quality by experienced speech pathologists. Systematic variation by patient, by sex, by disease, and by severity of physiological impairment will be sought by statistical analysis of the results, using analysis of variance, multiple regression analysis, and various non-parametric tests. Expected alterations in speech resulting from pulmonary disease have been predicted, and hypotheses based on these predictions will be tested by analysis of the observations made. Observations of changes and the mechanisms underlying these changes will provide a basis for effective management intervention.